1. Field of the Invention
The present invention relates in general to the field of information handling system power supply, and more particularly to a system and method for dynamic loop compensation for voltage mode control.
2. Description of the Related Art
As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems.
Information handling systems have grown in capability over time due, in part, to the increased number of calculations that are performed by the individual components used to build information handling systems, such as integrated circuits. However, over time, any particular integrated circuit may experience wide variations in the number of calculations that are performed. For example, a central processing unit (CPU) might perform at full capacity when executing intense mathematical operations yet use virtually no capacity when an information handling system is idle. As the number of calculations performed by an integrated circuit increases, the power consumed by the integrated circuit also typically increases. As a result, power demands for integrated circuits used in information handling systems can vary by an order of magnitude depending on the operations being performed by the information handling system. Typically, information handling systems include power regulating circuits that supply power to integrated circuits at a set voltage by varying the current applied at the integrated circuit. One example of a power regulating circuit is the Buck converter, which uses an inductor and two switches, such as a transistor and a diode. The switches open and close to alternately store energy from a power source into the inductor and discharge the inductor into the load.
In order to maintain the precise power requirements of an integrated circuit, power regulating circuits typically include a controller that uses an automatic compensation to control the application of power to the integrated circuit. For example, a Buck converter usually includes a feedback loop, such as a proportional-integral-derivative (PID) controller that drives the switches so that power applied to the integrated circuit stays within precise parameters. Although the feedback loop may use an analog circuit, typically the analog circuit is converted to digital control parameters used by a digital controller running on a microprocessor, microcontroller, state machine or other digital control embodiment. One difficulty with automatic compensation of a power regulator is that the compensation required for a lightly loaded voltage regulator is often vastly different from a heavily loaded voltage regulator. For example, the operation of a Buck converter in the continuous conduction mode (CCM) in which current remains greater than zero during each commutation cycle is very different from the discontinuous conduction mode (DCM) in which current is zero during a portion of each commutation cycle. The poles and zeros of the plants in a DCM system are not the same as those in a CCM system. As a result, Buck converters are often controlled with non-optimal compensation for both DCM and CCM operations to provide a sufficient stability margin for both cases.